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D - Effective diameter of driver, in meters |
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D2D - "Data to data" connection of an alarm/remote starter to bypass module. |
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DAC (D/A) - Digital to analog converter. A component or circuit that is used to derive or convert an analog signal from a digital one. |
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Damping - The reduction of the magnitude of resonance by the use of some type of material. |
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Damping Factor - The ratio of rated load impedance to the internal impedance of an amplifier. The higher the value, the more efficiently an amplifier can control unwanted movement of the speaker coil. A high damping factor is crucial for large speakers that reproduce bass. |
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DAT - Digital Audio Tape. |
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dBr - A unit of measurement that indicates the decibel level relative to a reference level. |
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DC/DC Converter - A group of components within an amplifier that converts battery voltage (DC) into AC so that it can be increased by the switching devices and transformer and converted back to DC (rectified) to provide higher voltage to drive the amplification stage. |
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Decade - A measurement equal to the low pass frequency being ten times the high pass frequency, which is relevant in a passive band pass crossover. The difference between 500 Hz and 5000 Hz is equal to 1 decade. |
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Decibel (dB) - A unit of measurement for the ratio of loudness. The threshold of hearing is 0 dB. One dB SPL is the smallest audible difference in sound level. more info |
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Detent Controls - A detent knob has precise click-stops at regular points to indicate how much the control has been turned up or down. |
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Deutsche Industrie Normen (DIN) - German (European) industrial standards. DIN size refers to the stereo size that fits most European automobiles. |
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Diaphragm - A thin, semi-rigid membrane that vibrates to produce or transmit sound waves; the part of a loudspeaker attached to the voice coil that moves to produces sound, usually in the shape of a cone or dome.
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Dielectric - An insulating material with low electrical conductivity. |
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Diffraction - A change in the direction of a sound wave that is caused by the sound wave moving past an obstacle. |
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Digital Output - An output where the signal is in digital form to allow external processing before being converted to an analog signal. |
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Digital Time Delay - A component that electronically delays the audio signals (in milliseconds) to provide surround type sound as well as compensate for speaker placements. |
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Digital Time Delay Gain Control - The control that lets you select how much of the whole of the audio signal to be treated with digital time delay. |
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Diode - An electrical circuit element that allows current to flow in one direction. |
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Direct Current (DC) - An electrical current that flows in one direction. |
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Directional / Directionality - The angle at which a speaker disperses sound. Higher frequencies are narrower than lower frequencies. Tweeters are more directional than woofers. |
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Discharge - In a capacitor, the release of stored energy to a load. In a battery, the conversion of chemical energy to electrical energy. |
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Dispersion - Distribution of sound from a speaker. |
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Distortion - Sound that is modified or changed in some way. Measured as a percentage of the whole signal. |
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Diversity Tuner - An FM tuning method which employs two antennas. The tuner can switch between the two antennas in order to attain better reception. |
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DIY - Abbreviation for Do It Yourself. |
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DMM - Digital Multimeter. A digital meter that gives a precise reading of voltage, current, or resistance (ohms). |
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Dolby Digital - Is a five-channel system consisting of left, center, right and left rear, right rear channels. All processing is done in the digital domain. Unlike Dolby Prologic in which the rear effects channels are frequency limited to approx. 100-7000Hz, Dolby Digital rear channels are specified to contain the full 20-20Khz frequency content. The AC3 standard also has a separate subwoofer channel for the lowest frequencies. |
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Dolby Digital EX Surround (Dolby Digital 6.1) - Adds a rear center channel to the existing left, center, right and rear speakers. This format requires a 6.1 processor or receiver and DVDs that are 6.1 encoded.
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Dolby Noise Reduction - A patented noise reduction system that increases dynamic range and signal-to-noise ratio of Dolby encoded media. |
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Dolby Prologic - Is a four-channel system consisting of a left, center, right and rear channel with the single rear channel typically played through two speakers. |
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Dome - A convex speaker shape usually used for tweeters. |
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Door Lock Solenoid - The proper name for the electric bi-directional actuator used to provide powered control vehicle door locks. Also called a Door Lock Actuator. |
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Dot Matrix Display - A display type that employs regularly spaced patterned grids of point-source lighting elements. As a result, characters displayed have greater resolution than a segmented display. |
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Double DIN - Twice the height of the standard DIN dimensions; width is standard DIN width. |
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DPDT - Double Pole Double Throw. A term used to describe a relay that has two separate poles or contacts and can throw or make electrical contact with two separate stationary contacts. |
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Driver - Synonymous with loudspeaker. The term also refers to a loudspeaker being coupled to a horn for acoustic coupling and controlled dispersion of sound. |
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DSP - Digital Signal Processing (or Processor). A type of processing accomplished by a microcomputer chip specifically designed for signal manipulation, or a component using such processing. The term is often misused as a synonym for ambience synthesizer; however, DSP can do much more than sound field creation. |
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DTS - Digital Theater System. A multi-channel encoding/decoding system. Used in some movie theaters and DVDs. Included in some home-theater processors and DVD players. A competitor to Dolby Digital. |
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Dual Mode - An amplifier configuration in which both a stereo speaker pair and mono speaker system (usually a subwoofer) are simultaneously powered by a stereo amplifier. |
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Dust Cap - Part of the speaker that keeps foreign material from falling into the voice coil, which could hinder the speaker's movement. |
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DVD - Digital Video Disc or Digital Versatile Disc is a format of optical disc storage medium, with a greater audio-visual data storage capacity than that of the compact disc (CD) of the same dimensions. |
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Dynamic Noise Reduction (DNR) - A signal-processing circuit that reduces
the level of high frequencies (hiss). Unlike Dolby Noise Reduction, DNR does not require
processing during recording. |
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Dynamic Range - The difference between the softest and loudest portions of sound that an amplifier or recorder can reproduce within an acceptable range of distortion. Expressed in decibels, the higher the number the better. |
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Dynamic Range Suppression - A signal compression technique which raises the level of lower passages without affecting overall volume. Especially useful with high noise levels, such as a moving vehicle. |
